[Intercellular serine proteinases from spore-forming bacilli].

Some physico-chemical properties, immunological reactions, structural, functional and evolutionary features of intracellular serine proteinases from spore-forming bacilli were studied. These enzymes belong to an individual subfamily of serine proteinases and in terms of their structure and evolution are most closely related to secretory subtilisins. Intracellular serine proteinases are found in a wide variety of microorganisms--from the spore-forming bacilli to Escherichia coli and are characterized by a higher (as compared to secretory subtilisins) rate of evolution due to a more rigid selective control of the structure and function of intracellular enzymes. Active intracellular proteinases have a unique dimeric structure, which allows to exclude random proteolysis of native proteins in vivo. Secretory subtilisins and intracellular bacillary serine proteinases are coded by separate closely related structural genes, whose presence in the bacillary genome can be explained by duplication of the precursor gene. The existence of duplicated genes of serine proteinases provides sufficient evidence for the marked structural divergence and a high rate of evolution of secretory subtilisins.